GB2374965A

GB2374965A - Individual monitoring of a particular animal selected from a group of animals

Info

Publication number: GB2374965A
Application number: GB0110142A
Authority: GB
Inventors: Brian Reed; Edward James Badcock
Original assignee: RE TECH ELECTRONICS Ltd
Current assignee: RE TECH ELECTRONICS Ltd
Priority date: 2001-04-25
Filing date: 2001-04-25
Publication date: 2002-10-30
Anticipated expiration: 2021-04-25
Also published as: GB2374965B; GB0110142D0

Abstract

Apparatus 1 is shown for individual monitoring of a particular animal selected from a group 2 of laboratory animals 3a 3b, 3c, each animal carrying an individual monitor (Figure 2) operable to respond to a personal code signal. The apparatus 1 comprises a cage antenna structure 4 defining a space 5 within which the group 2 of animals is disposed, a pulse moderator in the form of a decoder 6 for emitting a burst of electromagnetic energy as well as a personal code signal addressed to the individual monitor of a selected animal of the group 2, and a data collection station 7 in the form of a programable microprocessor, which serves as a data management system. The antenna 4 comprises four antenna coils 8a, 8b, 8c. A co-axial power cable 9 connects the antenna 4 with the decoder 6, by way of a connection 15, and a similar cable 11 connects the decoder 6 with the data collection station 7. The combined length of cables 10 and 11 may be up to 100metres, depending on cable grade.

Description

APPARATUS FOR INDIVIDUAL MONITORING OF A PARTICULAR ANIMAL SELECTED FROM A GROUP OF ANIMALS This invention relates to apparatus for individual monitoring of a particular animal selected from a group of laboratory animals.

There is a long-standing requirement for apparatus to facilitate monitoring key physiological and behavioural parameters (particularly body temperature and spontaneous activity) in groups of small laboratory animals over many months. The ability to monitor such parameters in unrestrained subjects has widespread implications for maximising the information gained from animals undergoing scientific procedures as well as improving their welfare. The invention provided low cost apparatus, attractive for example, to research groups for whom cost currently precludes the use of remote monitoring equipment.

The present invention comprises apparatus for individual monitoring of a particular animal selected from a group of laboratory animals, each animal carrying an individual monitor operable to respond to a personal code signal.

The apparatus comprising an antenna defining a space within which the group of animals is disposed, means for emitting a burst of electromagnetic energy as well as a personal code signal addressed to the monitor of a selected animal of the group, in order to initiate a response signal therefrom, which response signal incorporates monitored data obtained from the selected animal, whereby the antenna receives said response signal, a data collection station, and means whereby the data monitoring response signal is transmitted to said data collection station.

The antenna preferably comprises a cage antenna. The means for emitting a bursting electromagnetic energy conveniently comprises a pulse modulator, preferably a decoder.

The invention also comprises the apparatus in combination with animals carrying individual monitors operable to respond to personal code signals emitted by the apparatus.

The individual monitors may be operable to monitor temperatures of the animals. iL L 1. 1 The monitors may comprise subcutaneous implants, each of which may comprise a power source, an antenna, and an electronic control circuit for transmitting data signals by way of said antenna.

dz An embodiment of each aspect of the invention will now be described by way of example only, with reference to the accompanying drawings wherein :- Figure 1 illustrates the combination of apparatus and a group of monitor implanted animals, Figure 2 is a block diagram of an animal subcutaneous implant 20, Figure 3 is a block diagram of the decoder 6, and Figure 4 illustrates, in detail, related circuitry.

With reference to Figure 1, apparatus 1 is shown for individual monitoring of a particular animal selected from a group 2 of laboratory animals (rodents) 3a, 3b, 3c, each animal carrying an individual monitor (Figure 2) operable to respond to a personal code signal.

The apparatus 1 comprises a cage antenna structure 4 defining a space 5 within which the group 2 of animals is disposed, a pulse modulator in the form of a decoder 6 for emitting a burst of electromagnetic energy as well as a personal code signal addressed to the individual monitor of a selected animal of the group 2, and a data collection station 7 in the form of a programable personal computer, which serves as a data management system.

The antenna 4 comprises three antenna coils 8a, 8b, 8c. A co-axial power cable 9 connects the antenna 4 with the decoder 6, by way of a connection 15, and a data cable 11 connects the decoder 6 with the data collection station 7. The combined length of cable 10 may be up to 100metres, depending on cable grade.

Figure 2 illustrates an animal subcutaneous implant 20. The implant 20 comprises a biocompatibly coated sealed unit of cylindrical form, typically ca, 15. 0mm is diameter and 4. 00mm thick, containing (in this example) two tuned antenna coils L1, dz disposed orthogonally, and associated electronic control circuitry. Preferably three antenna coils are employed, thus allowing the implant to operate in any orientation. However, for most applications, a single antenna coil is sufficient.

The implant 20 is energised by a short burst of low frequency electromagnetic energy from the decoder 6. Frequencies in the range of 100 to 300Khz are normally used.

After the energising burst, an amplitude modulated digital code is sent to the implant 10 after it has been energised. This code identifies which implant is required to report, and what information is required.

If the digital code transmitted corresponds to the implant's identify, the implant 20 replies with a digital code transmitted by pulsing current in the coil antennas. Ll, dz The recovered field is rectified by diodes D and D, of the implant 20, and the electrical energy is stored in capacitor C. This is regulated to a lower, more suitable voltage for use by the electronic circuit. A reset generator 21 triggers the circuit once the voltage is above a predetermined level.

A simple comparator 22 detects the amplitude modulated code from the decoder 6 and feeds it to a microprocessor 23. The circuit includes a supply regulator 26. If the code so detected corresponds to that stored in the microprocessor memory, the implant 20 replies to the decoder 6 by pulsing current in the tuned coil antennas L1, 1.

Temperature of the animal is measured by passing a current from an internal high precision voltage source 24 through a temperature sensor 25, which comprises a diode or calibrated thermistor. The voltage across the sensor 25 is measured by an analogue to digital converter using the same voltage source as its reference 24.

In a modification, a coil antenna is either wound around the cage antenna 4, or is fitted to an external'former'into which the unmodified cage is placed, allowing the subject cage to be easily exchanged for another.

A small number of passive electronic components are used to tune and match the antenna 14 to the connecting cable 10. These components are housed in the connector cage 15. The cable is attached to the antenna 4 via sealed coaxial connectors 16. The cable and connectors are standard low cost coaxial equipment, commonly used for professional and consumer applications.

No other external power is required other than that available from the decoder 6 via the connecting cables 10,11.

With reference to Figure 3, the decoder 6 is contained in a small, (typically 300mm square) metal enclosure. It connects to the cage antenna 4 by way of the coaxial lead 10 and connector 15 to a power source, normally a mains supply, and to the data management system, i. e. the personal computer 7.

The decoder provides a high frequency current drive to the cage antenna 4 via the cable 10. The power available is programmed to match the size of the antenna. The power is limited to a maximum of 10.0 watts.

The circuit of Figure 3 includes a microprocessor 30, a power amplifier 31, with a power control 32, a low-pass filter 33 and a diplexer 34 connected to the cage antenna 4. The circuit also includes a detector 35, a band-pass filter 36, and an amplifier 37, also connected to the diplexer 34. The microprocessor 30 provides a data link with the data collection station 7 (Figure 1) by way of interface connection 38. The detector 35 has data (39) and signal level (40) connections with the microprocessor 30.

The diplexer 34 switches the decoder 6 between the functions of sending the energising burst and code signal to the implant 20 and of receiving the data signal from the implant.

The energising pulse and the identity code are transmitted by the decoder 6, as an

amplitude modulated burst of high frequency, in the range of 100 to 300Khz. The return pulses of high frequency from the selected implant 20 are amplified, filtered, and amplitude detected by detector 35 to recover the data, and to prove a measure of signal strength. The information received from the implant 20 is decoded and sent to the data computer 7 as a serial digital code via the interface 38.

A programme running in the equipment 7 :- allows the monitoring schedule to be set-up, and then rapidly addresses each implant 20 in turn, requesting information from it. Up to sixteen implants per cage antenna 4 may be addressed within a second. calibrates the temperature measurement, and records it together with the cage and implant identity. stores the signal strength level for each implant 20, and compares it with previous measurements to produce and record, a measure of activity. displays a graphical representation of the measurements being made. allows post hoc analysis of the recorded data.

The invention has a combination of the following features :-

'the ability to monitor groups of unrestrained animals batteryless operation enabling long term studies, and reuse of implants low cost of implants and cage antenna modifications improved accuracy when compared to currently available equipment By increasing the capacity of the storage capacitor C, (Figure 2), in an implant 20, allows more energy to be stored, and so additional electronic circuits may be added. This enables other functions to be carried out in the period between energising pulses :-

for example heart rate may be monitored, reported and recorded using the additional stored energy to power a low consumption amplifier, together with external electrodes to monitor ecg. (electrocardiogram) signals. The time between the peaks of the signals may be stored, to enable a value for heart rate to be calculated.

Activity or how much, and how often an animal moves may be more accurately assessed by using a tilt switch or high sensitivity accelerometer.

The non-implanted equipment may also be used to monitor a much simpler, single subject implant, by additions to the control programme running in the computer 7. This single implant would not require the data receiving circuitry, or microprocessor, and so can be much smaller, lighter and less expensive.

Figure 3 illustrates circuitry, showing related parts of the invention in further detail.

Claims

1. Apparatus for individual monitoring of a particular animal selected from a group of laboratory animals, each animal carrying an individual monitor operable to respond to a personal code signal, the apparatus comprising an antenna defining a space within which the group of animals is disposed, means for emitting a burst of electromagnetic energy as well as a personal code signal addressed to the monitor of a selected animal of the group, in order to initiate a response signal there from, which response signal incorporates monitored data obtained from the selected animal, whereby the antenna is responsive to said response signal, a data collection station, and means whereby the date monitoring response signal is transmitted to said data collection station.

2. Apparatus as claimed in Claims 1, wherein the means for emitting a burst of electromagnetic energy comprise a pulse modulator.

3. Apparatus as claimed in Claim 2, wherein the pulse modulator comprises a decoder.

4. Apparatus as claimed in any one of Claims 1 to 3 wherein the antenna comprises a cage antenna.

5. Apparatus as claimed in any one of Claims 1 to 4, in combination with animals carrying individual monitors operable to respond to personal code signals emitted by the apparatus.

6. The combination of Claim 5, wherein the individual monitors are operable to monitor temperature of the animals.

7. The combination of Claims 5 or 6, wherein the individual monitors comprise subcutaneous implants.

8. The combination of Claim 7 where each subcutaneous implant comprise a power source, an antenna, and an electronic control circuit for transmitting data signals by way of the said antenna.

9. The combination claimed in Claim 7 wherein the antenna of the implant has at least two antenna coils disposed orthogonally.

10. The combination claimed in Claim 8 wherein the antenna of the implant has three antenna coils disposed orthogonally.

11. Apparatus as claimed in any one of Claims 1 to 4, substantially as hereinbefore described, with reference to the accompanying drawings.

12. The combination claimed in any one of Claims 5 to 10, substantially as hereinbefore described, with reference to accompanying drawings.